Medical image diagnostic apparatus

ABSTRACT

According to one embodiment, a medical image diagnostic apparatus includes a storage memory, processing circuitry, and a display. The storage memory stores data of a plurality of FFR distribution maps constituting a time series regarding a coronary artery, and data of a plurality of morphological images corresponding to the time series. The processing circuitry converts the plurality of FFR distribution maps into a plurality of corresponding color maps, respectively. The display displays a plurality of superposed images obtained by superposing the plurality of color maps and the plurality of morphological images respectively corresponding in phase to the plurality of color maps. The display restricts display targets for the plurality of color maps based on the plurality of FFR distribution maps or the plurality of morphological images.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of and claims the benefit of priorityunder 35 U.S.C. § 120 from U.S. Ser. No. 15/653,206 filed Jul. 18, 2017which is a divisional of U.S. Ser. No. 15/241,705 filed Aug. 19, 2016,now U.S. Pat. No. 9,786,068 issued Oct. 10, 2017, which is a divisionalof U.S. Ser. No. 14/725,426 filed May 29, 2015, now U.S. Pat. No.9,471,999 issued Oct. 18, 2016, the entire contents of which isincorporated herein by reference. U.S. Ser. No. 14/725,426 is a NationalStage of PCT/JP2013/082372 filed Dec. 2, 2013 which was not publishedunder PCT Article 21(2) in English and claims the benefit of priorityfrom prior Japanese Patent Application No. 2012-263353 filed Nov. 30,2012 and Japanese Patent Application No. 2013-249059 filed Dec. 2, 2013,the entire contents of each of which are incorporated herein byreference.

FIELD

Embodiments described herein relate generally to a medical imagediagnostic apparatus.

BACKGROUND

Recently, a Fractional Flow Reserve (FFR) analysis technique using aComputed Tomography (CT) apparatus has been developed. This techniquegenerates a coronary artery shape model from CT volume data regarding acoronary artery that is collected by the CT apparatus, simulates a bloodflow, and calculates a pressure value in the coronary artery.Information useful for angiostenosis treatment, such as FFR, can benoninvasively obtained based on the pressure value in the coronaryartery. At present, the FFR analysis technique is applicable to atemporal change of the FFR result considering the heart beats of thecoronary artery.

However, the heart beats at a short time interval, so the FFR valuechanges quickly on a display regarding a temporal change of the FFRresult of the coronary artery. For this reason, an FFR value whichshould be noted, and the position of the FFR value may be missed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an example of the arrangement of amedical image diagnostic apparatus according to an embodiment.

FIG. 2 is a flowchart showing processing procedures in the specificperiod display mode of a medical image diagnostic apparatus 1 accordingto this embodiment.

FIG. 3 is a flowchart showing processing procedures in the thinningdisplay mode of the medical image diagnostic apparatus according to thisembodiment.

FIG. 4 is a flowchart showing processing procedures in the local displaymode of the medical image diagnostic apparatus according to thisembodiment.

FIG. 5 is a view showing an example of display of a superposed imageobtained by superposing a morphological image and a color map on amyocardial perfusion image.

FIG. 6 is a view showing an example of display of a superposed imageobtained by superposing a morphological image and a color map on a polarmap. FIG. 7 is a flowchart showing processing procedures in the bloodvessel display mode of the medical image diagnostic apparatus accordingto this embodiment.

FIG. 8 is a view showing an example of a 3D graph in the blood vesseldisplay mode.

FIG. 9 is a flowchart showing processing procedures in the FFRvalue-limited mode of the medical image diagnostic apparatus accordingto this embodiment.

FIG. 10 is a block diagram showing an example of the arrangement of amedical image diagnostic apparatus according to a modification of thisembodiment.

DETAILED DESCRIPTION

In general, according to one embodiment, a medical image diagnosticapparatus includes a storage memory, processing circuitry, and adisplay. The storage memory stores data of a plurality of FractionalFlow Reserve (FFR) distribution maps constituting a time seriesregarding a coronary artery, and data of a plurality of morphologicalimages corresponding to the time series. The processing circuitryconverts the plurality of FFR distribution maps into a plurality ofcorresponding color maps, respectively. The display displays a pluralityof superposed images obtained by superposing the plurality of color mapsand the plurality of morphological images respectively corresponding inphase to the plurality of color maps. The display restricts displaytargets for the plurality of color maps based on the plurality of FFRdistribution maps or the plurality of morphological images.

A medical image diagnostic apparatus according to an embodiment will nowbe described with reference to the accompanying drawings. In thefollowing description, the same reference numerals denote parts havingalmost the same functions and arrangements, and a repetitive descriptionis made only if necessary.

FIG. 1 is a block diagram showing an example of the arrangement of amedical image diagnostic apparatus 1 according to this embodiment. Asshown in FIG. 1, the medical image diagnostic apparatus 1 includes acommunication interface circuitry 11, a storage memory 12, an LUTgeneration circuitry 13 (correspondence table generation circuitry 13),a color map conversion circuitry 14, a control circuitry 15, an inputcircuitry 16, a blood vessel area extraction circuitry 17, a displayrange setting circuitry 18, an image selection circuitry 19, and adisplay 20.

The medical image diagnostic apparatus 1 according to this embodiment isconnected to external apparatuses such as a CT (Computed Tomography)apparatus, a medical image processing apparatus, and a PACS (PictureArchiving and Communication System) via networks such as a LAN (LocalArea Network) and a public electronic communication network. The medicalimage diagnostic apparatus 1 includes the communication interfacecircuitry 11 for connecting to an external apparatus via a network. Thecommunication interface circuitry 11 includes, for example, a connectorcircuitry (not shown) for connecting the medical image diagnosticapparatus 1 to an external apparatus or the like via a cable or thelike, and a wireless signal reception circuitry (not shown) forreceiving a wireless signal from an external apparatus. The medicalimage diagnostic apparatus 1 transmits/receives data to/from an externalapparatus via the communication interface circuitry 11 under the controlof the control circuitry 15 (to be described later).

The storage memory 12 includes, for example, a semiconductor storagedevice such as a Flash SSD (Solid State Disk) serving as a semiconductorstorage element, and an HDD (Hard Disk Drive). Under the control of thecontrol circuitry 15, the storage memory 12 stores data of a pluralityof types of images transmitted from external apparatuses. A plurality ofimages include a plurality of morphological images (to be simplyreferred to as a plurality of morphological images hereinafter), aplurality of FFR (Fractional Flow Reserve) distribution maps (to besimply referred to as a plurality of FFR distribution maps hereinafter),and a plurality of myocardial perfusion images regarding a cardiacmuscle to which the coronary artery of an object supplies blood. Aplurality of medical images of these types each constitute a time seriesregarding the coronary artery of an object. Note that a myocardialperfusion image may be an image generated not only by a CT apparatus butalso by another modality such as an MRI apparatus. Note that theabove-mentioned images handled in the medical image diagnostic apparatus1 are 3D image data, unless otherwise specified. A morphological imageincludes a 3D coronary artery model. A time series regarding thecoronary artery of an object includes at least a plurality of phases inone cycle of heart beats of the object. A plurality of phases regardinga morphological image include at least a plurality of phases regardingan FFR distribution map. The range of an object including a coronaryartery in a morphological image includes at least the range of theobject including the coronary artery in an FFR distribution map.

The storage memory 12 stores data of an LUT (Look Up Table) generated bythe LUT generation circuitry 13 (to be described later). The LUT is atable that associates pieces of color information with a plurality ofFFR values, respectively. The color information includes, for example,the type of color, the density of the color, and the fill effect of thecolor. Note that the storage memory 12 may store data of an LUT thatassociates in advance pieces of color information with a plurality ofFFR values, respectively. At this time, the minimum value of the FFRvalue is 0 and its maximum value is 1 in the LUT stored in advance inthe storage memory 12.

Also, the storage memory 12 stores data regarding detailed conditions ofa display mode (to be described later) input by a user via the inputcircuitry 16. Note that the storage memory 12 may hold, without change,data of the aforementioned plurality of types of medical images thathave been received via the communication interface circuitry 11 andstored, or the data may be erased in response to the end of a useroperation to the medical image diagnostic apparatus 1.

The LUT generation circuitry 13 is processing circuitry that generatesan LUT based on a master table and data of an LUT generation target. TheLUT generation circuitry 13 reads a program corresponding to a LUTgeneration function from storage memory 12, and executes the program torealize the LUT generation function. The master table is a table thatassociates, for example, 10 pieces of color information respectivelywith 10 FFR values obtained by division into 10 equal parts from aminimum value to a maximum value. The equal division count, the colorinformation assignment order, the number of pieces of color information,and the like can be properly changed in accordance with userinstructions via the input circuitry 16. First, the LUT generationcircuitry 13 specifies the minimum and maximum values of the FFR valuefrom data of an LUT generation target. The LUT generation targetincludes, for example, 1) data of a plurality of FFR distribution maps,2) data of ranges respectively set from a plurality of color maps or aplurality of morphological images by the display range setting circuitry18, and 3) data of a plurality of color maps extracted from a pluralityof color maps by the image selection unit 19 (to be described later).The interval between the minimum and maximum values of the FFR value isequally divided by the division count of a value in the master table.Then, the LUT generation circuitry 13 adds pieces of color informationdefined in the master table to the minimum value of the FFR value, themaximum value of the FFR value, and the plurality of FFR values obtainedby equally dividing the interval, respectively, thereby generating anLUT.

The color map conversion circuitry 14 is processing circuitry thatconverts a graph regarding the FFR value into a color graph to whichcolor information is added based on the LUT. The color map conversioncircuitry 14 reads a program corresponding to a color map conversionfunction from storage memory 12, and executes the program to realize thecolor map conversion function.

The control circuitry 15 is processing circuitry that controls therespective circuitry of the medical image diagnostic apparatus 1 basedon input information received from the input circuitry 16. The controlcircuitry 15 reads a program corresponding to a control function fromstorage memory 12, and executes the program to realize the controlfunction. The input information input from the input unit 16 istemporarily stored in a memory circuit included in the control circuitry15.

The input circuitry 16 functions as an interface for acceptinginstruction information from the user to the medical image diagnosticapparatus 1. As the input circuitry 16, input devices such as a mouse,keyboard, trackball, touch panel, and button are properly usable.

More specifically, the input circuitry 16 accepts an input of a displaymode for the FFR result of a coronary artery by the user. The FFR resultof a coronary artery represents a temporal change of the FFR regardingthe blood vessel area of the coronary artery in one cycle of heartbeats. Display modes for the FFR result of the coronary artery include aspecific period display mode, a thinning display mode, a local displaymode, a blood vessel display mode, and an FFR value-limited mode. Thesedisplay modes are display modes provided by the medical image diagnosticapparatus 1 in order to improve the image interpretation efficiency ofthe FFR result of a coronary artery by the user. The input circuitry 16accepts an input of detailed conditions in each mode by the user. Eachmode and its detailed conditions will be described later.

The input circuitry 16 also accepts an input of a display target for aplurality of color maps on the display 20.

For example, the input circuitry 16 accepts an input of the range of theabove-mentioned display target by a user operation on a morphologicalimage or an FFR distribution map. For example, the user can input therange of the above-mentioned display target by designating a range wherehe wants to check a temporal change of the FFR value by a mouseoperation on a morphological image or an FFR distribution map. At thistime, the user may designate the range of the target for each image.Alternatively, the user may designate the range of the target on arepresentative image out of a plurality of morphological images or aplurality of FFR distribution maps, and the range designated on therepresentative image may be applied to other images.

Instead, the display 20 may display electrocardiographic waveforms (orelectrocardiographic waveform models) corresponding to a plurality ofmorphological images, and the FFR distribution map of theabove-mentioned display target may be designated by a user operation onthe displayed electrocardiographic waveform.

In addition, the input circuitry 16 accepts an input for setting ranges(to be referred to as color display ranges hereinafter) to be displayedin color on the display 20 from a plurality of color maps, respectively.For example, when the display range setting circuitry 18 sets a colordisplay range based on the FFR value, the user can set an FFR valuerange by inputting at least one of the upper and lower limit values ofan FFR value to be displayed. For example, the user sets an FFR value of0.8 or less, and can set a color display range where it can be estimatedthat angiostenosis is severe.

Further, the input circuitry 16 accepts display/non-display userinstructions regarding a myocardial perfusion image and polar map to thedisplay 20 (to be described later). The input circuitry 16 accepts aswitching operation of each display mode described above and a switchingoperation between setting and cancellation of each display mode.

The blood vessel area extraction circuitry 17 is processing circuitry.The processing circuitry reads a program corresponding to a function ofthe blood vessel area extraction circuitry 17, and executes the programto realize the function of the blood vessel area extraction circuitry17. The blood vessel area extraction circuitry 17 extracts a bloodvessel area from a morphological image based on a luminance value. Then,the blood vessel area extraction circuitry 17 specifies, from theextracted blood vessel area, at least one of an angiostenosis position,a blood vessel branch position, the position of a blood vessel having apredetermined width or more, and the position of a blood vessel having apredetermined width or less. The angiostenosis position can be specifiedaccording to, for example, the change amount of the inside diametervalue of an extracted blood vessel area. This is because the insidediameter value of a blood vessel does not greatly vary in a range otherthan a branch position and the end of a blood vessel in a coronaryartery, and a range having a large change amount of the inside diametervalue is highly likely to be a stenosis range. As for the blood vesselbranch position, for example, a center line is specified from anextracted blood vessel area, and the blood vessel branch position can bespecified from a position where the center line branches. The positionof a blood vessel having a predetermined width or more, or apredetermined width or less can be specified based on supplementaryinformation, imaging conditions, or the like.

The display range setting circuitry 18 is processing circuitry. Theprocessing circuitry reads a program corresponding to a function of thedisplay range setting circuitry 18, and executes the program to realizethe function of the display range setting circuitry 18. The displayrange setting circuitry 18 sets display targets from a plurality ofcolor maps, respectively, based on the FFR value (in the FFRvalue-limited mode to be described later). The display range settingcircuitry 18 sets display targets from a plurality of color maps,respectively, based on an angiostenosis position, a blood vessel branchposition, and the position of a blood vessel having a predeterminedwidth or more, which have been extracted from a plurality ofmorphological images by the blood vessel area extraction circuitry 17(in the local display mode to be described later). A display rangesetting method by the display range setting circuitry 18 will bedescribed later.

The image selection circuitry 19 is processing circuitry that extractsthe color map of a display target from a plurality of color maps basedon the heart beat phase (specific period display mode to be describedlater). The image selection circuitry 19 reads a program correspondingto an image selection function from storage memory 12, and executes theprogram to realize the image selection function. An image selectionmethod by the image selection circuitry 19 will be described later.

The display 20 displays a plurality of superposed images obtained bysuperposing a plurality of color maps and a plurality of morphologicalimages corresponding in phase to the plurality of color maps. In thespecific period mode and the thinning mode (to be described later), thecolor map of a display target is a color map extracted by the imageselection circuitry 19. In the local display mode and the FFRvalue-limited mode (to be described later), the color map of a displaytarget includes all color maps. However, in each of a plurality of colormaps, only a color display range is displayed in color. In each mode,therefore, the display 20 displays a superposed image in which thedisplay targets for a plurality of color maps are restricted. Thedisplay 20 may display a plurality of superimposed images obtained bysuperimposing a plurality of color maps and a plurality of morphologicalimages corresponding in phase to the plurality of color maps.

The display 20 displays soft buttons and the like for accepting, fromthe user, a display mode switching operation and an operation to switchan LUT used for color map generation.

Next, the specific period display mode provided by the medical imagediagnostic apparatus 1 according to this embodiment will be explained.

(Specific Period Display Mode)

The specific period display mode is a mode in which a temporal change ofa superposed image in a specific period of one cycle of heart beats ofan object is displayed.

FIG. 2 is a flowchart showing processing procedures in the specificperiod display mode of the medical image diagnostic apparatus 1according to this embodiment. First, data of a plurality ofmorphological images and data of a plurality of FFR distribution mapsregarding the coronary artery of an object are received from externalapparatuses via the communication interface circuitry 11 (step S11). TheLUT generation circuitry 13 generates the first LUT based on theplurality of received FFR distribution maps (step S12).

Based on the first LUT, the color map conversion circuitry 14 convertsthe plurality of FFR distribution maps into a plurality of correspondingfirst color maps, respectively (step S13).

Then, a specific period is set (step S14). Specific periods are, forexample, the diastolic period of the heart, the systolic period of theheart, and a period designated by a user (to be referred to as auser-designated period hereinafter). The user-designated period can beset by, for example, designating a display start phase and a display endphase by the user on the moving image of a morphological image thatchanges over time. The diastolic period and systolic period of the heartcan be specified based on, for example, information equivalent to thephase of an electrocardiographic waveform added to each morphologicalimage.

The image selection circuitry 19 selects a plurality of first color mapscorresponding to a plurality of phases constituting the specific periodfrom the plurality of first color maps converted in step S13 (step S15).

The LUT generation circuitry 13 generates the second LUT based on FFRvalues included in the plurality of first color maps corresponding tothe plurality of phases constituting the specific period (step S16).

Based on the second LUT, the color map conversion circuitry 14 convertsthe plurality of FFR distribution maps into a plurality of correspondingsecond color maps, respectively (step S17).

The display 20 displays a plurality of superposed images obtained bysuperposing the plurality of color maps corresponding to the pluralityof phases constituting the specific period, and a plurality ofmorphological images respectively corresponding to the plurality ofcolor maps (step S18). At this time, the plurality of color mapscorresponding to the plurality of phases constituting the specificperiod correspond to the plurality of first color maps or the pluralityof second color maps. For example, when a color map used for a displayedsuperposed image is the first color map, if the user gives aninstruction to switch the color map in step S19, the display 20 switchesthe color map used for a superposed image from the first color map tothe second color map.

Every time the user gives a color map switching instruction, therespective circuitry repetitively execute the processing in step S18(step S19).

Next, the thinning display mode provided by the medical image diagnosticapparatus 1 according to this embodiment will be explained.

(Thinning Display Mode)

The thinning display mode is a mode in which temporal changes of aplurality of superposed images left after thinning processing on aplurality of superposed images corresponding to a plurality of phasesconstituting one cycle of heart beats of an object are displayed.

FIG. 3 is a flowchart showing processing procedures in the thinningdisplay mode of the medical image diagnostic apparatus 1 according tothis embodiment. First, data of a plurality of morphological images anddata of a plurality of FFR distribution maps regarding the coronaryartery of an object are received from external apparatuses via thecommunication interface circuitry 11 (step S21). The LUT generationcircuitry 13 generates the first LUT based on the plurality of receivedFFR distribution maps (step S22).

Based on the first LUT, the color map conversion circuitry 14 convertsthe plurality of FFR distribution maps into a plurality of correspondingfirst color maps, respectively (step S23).

The thinning ratio is set in accordance with a user instruction via theinput circuitry 16 (step S24). The image selection circuitry 19 selectsa plurality of first color maps from the plurality of first color mapsin accordance with the thinning ratio set in step S24 (step S25). TheLUT generation circuitry 13 generates the third LUT based on FFR valuesincluded in the first color maps selected in step S25 (step S26).

Based on the third LUT, the color map conversion circuitry 14 convertsthe plurality of FFR distribution maps into a plurality of correspondingthird color maps, respectively (step S27).

The display 20 displays a plurality of superposed images obtained bysuperposing the plurality of color maps selected from the plurality ofcolor maps in accordance with the thinning ratio set in step 524, and aplurality of morphological images respectively corresponding to theplurality of selected color maps (step 528). At this time, the pluralityof color maps correspond to the plurality of first color maps or theplurality of third color maps. For example, when a color map used for adisplayed superposed image is the first color map, if the user gives aninstruction to switch the color map in step S29, the display 20 switchesthe color map used for a superposed image from the first color map tothe third color map.

Every time the user gives a color map switching instruction, therespective circuitry repetitively execute the processing in step S28(step S29).

Next, the local display mode provided by the medical image diagnosticapparatus 1 according to this embodiment will be explained.

(Local Display Mode)

The local display mode is a mode in which a temporal change of asuperposed image in a specific range in the coronary artery of an objectis displayed.

FIG. 4 is a flowchart showing processing procedures in the local displaymode of the medical image diagnostic apparatus 1 according to thisembodiment. First, data of a plurality of morphological images and dataof a plurality of FFR distribution maps regarding the coronary artery ofan object are received from external apparatuses via the communicationinterface circuitry 11 (step S31). The LUT generation circuitry 13generates the first LUT based on the plurality of received FFRdistribution maps (step S32).

Based on the first LUT, the color map conversion circuitry 14 convertsthe plurality of FFR distribution maps into a plurality of correspondingcolor maps, respectively (step S33).

The type of a color display range is accepted via the input circuitry16. More specifically, the user selects at least one display range fromthe following four types of display ranges. The four types of displayranges are, for example, a range designated by a user (to be referred toas a user-designated range hereinafter), a range including the stenosissite of a blood vessel (to be referred to as a stenosis rangehereinafter), a range including the branch position of a blood vessel(to be referred to as a branch range hereinafter), and a range where theinside diameter of a blood vessel 1 s equal to or larger than a specificwidth (to be referred to as a specific blood vessel range hereinafter).

If the “user-designated range” is selected as the color display range(step S34), the display range setting circuitry 18 sets, as the colordisplay range, a range designated by the user on a morphological imageor an FFR distribution map (step S35).

If the “stenosis range” is selected as the color display range (stepS36), the blood vessel area extraction circuitry 17 extracts a bloodvessel area from a morphological image. An angiostenosis position isspecified from the extracted blood vessel area (step S37). The displayrange setting circuitry 18 sets, as the color display range, a rangeobtained by adding a predetermined margin in each of four directionsfrom the angiostenosis position (step S38). Note that the predeterminedmargin is stored in advance in the storage memory 12 and can be properlychanged in accordance with a user instruction via the input circuitry16.

If the “branch range” is selected as the color display range (step S39),the blood vessel area extraction circuitry 17 extracts a blood vesselarea from a morphological image. A blood vessel branch position isspecified from the extracted blood vessel area (step S40). The displayrange setting circuitry 18 sets, as the display range, a range of apredetermined size using the blood vessel branch position as the centerof the display (step S41). Note that the predetermined size is set to,for example, “a range of 5 cm from the blood vessel branch position”,and data of this setting is stored in advance in the storage memory 12.Note that data of the setting can be properly changed in accordance witha user instruction via the input circuitry 16.

If the display method is none of the above-described methods, the colordisplay range is a “specific blood vessel range”. The blood vessel areaextraction circuitry 17 extracts a blood vessel area from amorphological image. A specific blood vessel range is specified from theextracted blood vessel area (step S42). The specific blood vessel rangeis, for example, the range of a blood vessel area where the insidediameter is larger than a predetermined value, or the range of a bloodvessel area where the inside diameter of a blood vessel is smaller thana predetermined value. The display range setting circuitry 18 sets, asthe display range, a range obtained by adding a margin in each of fourdirections of a specific blood vessel range (step S43).

The display 20 sets the color display range as a display target, anddisplays superposed images obtained by superposing a plurality of colormaps and a plurality of morphological images respectively correspondingin phase to the plurality of color maps (step 544).

In steps S17, S27, and S44, the display 20 may display superposed imagesobtained by position matching and phase matching of a plurality ofmorphological images and a plurality of color maps with respect to aplurality of myocardial perfusion images. Similarly, in steps S17, S27,and S44, the display 20 may display superposed images obtained byposition matching and phase matching of a plurality of morphologicalimages and a plurality of color maps with respect to a plurality ofpolar maps. Display/non-display of these images can be properly switchedin accordance with a user instruction via the input circuitry 16.

FIG. 5 is a view showing an example of display of a superposed imageobtained by superposing a morphological image and a color map on amyocardial perfusion image. As shown in FIG. 5, a superposed imageobtained by superposing a morphological image (3D coronary artery model)and a color map on a myocardial perfusion image is displayed. As shownin FIG. 5, the partial range of the myocardial perfusion image may bedisplayed as the myocardial perfusion image. At this time, the displayedpartial range can be set in accordance with a user instruction via theinput circuitry 16. The display 20 may automatica y display a superposedimage so that the superposed image includes an ischemic area on themyocardial perfusion image. A color scale bar regarding the FFR value isdisplayed in accordance with an LUT used for conversion from an FFRdistribution map into a color map, and represents the magnitude of theFFR value by color. A color scale bar regarding the blood flow rate isapplied to the color display of a myocardial perfusion image, andrepresents the blood flow rate by color. In the display of FIG. 5, afunctional image regarding a cardiac muscle to which a coronary arterysupplies blood is displayed by position matching on a superposed imageregarding the coronary artery. The user can interpret a temporal changeof the FFR value of the coronary artery and a state change of thecardiac muscle together. This can improve the image interpretationefficiency and diagnosis accuracy by the user. Therefore, the myocardialperfusion image may be another image as long as it is a functional imagerepresenting the state of the cardiac muscle. Functional images may befunctional images generated by, for example, functional image diagnosisusing SPECT, delayed enhancement imaging using MRI, and functional imagediagnosis using PET. A functional image representing the state of thecardiac muscle may be, for example, a polar map corresponding to amyocardial perfusion image. At this time, the functional imagerepresenting the state of the cardiac muscle may be stored in thestorage memory 12 or stored in a PACS or the like connected via thecommunication interface circuitry 11.

FIG. 6 is a view showing an example of display of a superposed imageobtained by superposing a morphological image and a color map on a polarmap. At this time, assume that the storage memory 12 stores data of aplurality of polar maps corresponding to a plurality of myocardialperfusion images regarding a cardiac muscle to which the coronary arteryof an object supplies blood. As shown in FIG. 6, a superposed imageobtained by superposing a morphological image and a color map on a polarmap is displayed. A color scale bar regarding the FFR value is displayedin accordance with an LUT used for conversion from an FFR distributionmap into a color map, and represents the magnitude of the FFR value bycolor. A color scale bar regarding the blood flow rate is applied to thecolor display of a polar map, and represents the blood flow rate bycolor.

Next, the blood vessel display mode provided by the medical imagediagnostic apparatus 1 according to this embodiment will be explained.

(Blood Vessel Display Mode)

The blood vessel display mode is a mode in which a temporal change ofthe FFR result of each blood vessel in the coronary artery of an objectis displayed.

FIG. 7 is a flowchart showing processing procedures in the blood vesseldisplay mode of the medical image diagnostic apparatus 1 according tothis embodiment. First, data of a plurality of morphological images anddata of a plurality of FFR distribution maps regarding the coronaryartery of an object are received from external apparatuses via thecommunication interface circuitry 11 (step S61). The LUT generationcircuitry 13 generates the first LUT based on the plurality of receivedFFR distribution maps (step S62).

The blood vessel area extraction circuitry 17 extracts a blood vesselarea from a morphological image, and extracts the center line of a bloodvessel from the extracted blood vessel area (step S63). Then, the branchposition of the extracted center line of the blood vessel is specified.The extracted blood vessel area is divided into a plurality of bloodvessel portions in accordance with the branch position of the centerline of the blood vessel (step S64). A blood vessel portion to bedisplayed is set in accordance with a user instruction via the inputcircuitry 16 (step S65). The blood vessel portion can be set by, forexample, a mouse operation by the user on a displayed morphologicalimage. The blood vessel area extraction circuitry 17 sets a plurality ofpoints alone the center line of the blood vessel using, as a startpoint, a branch position on the center line of the blood vessel of theblood vessel portion to be displayed (step S66).

The display 20 displays a 3D graph defined by three axes that are thedistance, the lapse of time, and the FFR value (step S67). The distanceis a distance from a predetermined position of the blood vessel portionto be displayed, for example, from a blood vessel branch position toeach of a plurality of points. The lapse of time is the lapse of timefrom a reference that is predetermined time of the time series. Thepredetermined time is, for example, the systolic end or diastolic end ofthe heart. The FFR value is the FFR value of a given point at giventime.

FIG. 8 is a view showing an example of a 3D graph. As shown in FIG. 8,the 3D graph may be a color graph in accordance with the FFR value. Atthis time, an LUT used for the color graph display is, for example, thefirst LUT. This LUT may be an LUT generated by the LUT generationcircuitry 13 based on an FFR value included in a blood vessel portion tobe displayed. A color scale bar regarding the FFR value represents colorinformation corresponding to the FFR value based on an LUT used for thecolor graph. In the blood vessel display mode, the 3D graph suffices tobe a graph from which the user can easily interpret the time inpulsation, a position at a blood vessel portion to be displayed, and themagnitude of the FFR value. This graph may be, for example, a 2D colormap obtained by converting, by the color map conversion circuitry 14 inaccordance with the first LUT, a 2D map defined by two axes that are thelapse of time and a distance from a branch position.

(FFR Value-Limited Mode)

The FFR value-limited mode is a mode in which a temporal change of asuperposed image in a specific FFR value range in the coronary artery ofan object is displayed.

FIG. 9 is a flowchart showing processing procedures in the FFRvalue-limited mode of the medical image diagnostic apparatus 1 accordingto this embodiment. First, data of a plurality of morphological imagesand data of a plurality of FFR distribution maps regarding the coronaryartery of an object are received from external apparatuses via thecommunication interface circuitry 11 (step S71). The LUT generationcircuitry 13 generates the first LUT based on the plurality of receivedFFR distribution maps (step S72).

Based on the first LUT, the color map conversion circuitry 14 convertsthe plurality of FFR distribution maps into a plurality of correspondingfirst color maps, respectively (step S73).

An input of an FFR value range for setting a color display rangeaccepted in accordance with a user instruction via the input circuitry16 (step S74).

The display range setting circuitry 18 extracts, from a plurality ofcolor maps, ranges corresponding to the FFR value range set in step S74(or step S77) (step S75). The extracted range serves as a color displayrange.

The display 20 sets the color display range as a display target, anddisplays superposed images obtained by superposing a plurality of colormaps and a plurality of morphological images respectively correspondingin phase to the plurality of color maps (step S76).

If the user changes the FFR value range, the process shifts to step S75(step S77).

Note that the specific period display mode and the thinning display modeout of the plurality of display modes described above are modes in whicha superposed image to be displayed is limited. The local display modeand the FFR value-limited mode are modes in which the range where animage is displayed in the color of a color map displayed over amorphological image is limited. These modes are not only singly used,and a display in a combination of these modes is possible. For example,when the specific period display mode and the FFR value-limited mode arecombined, a superposed image corresponding to a specific periodcomplying with a user instruction is displayed, and the color displayrange of a superposed color map is limited.

The medical image diagnostic apparatus 1 having the above-describeddisplay modes according to this embodiment can obtain the followingeffects.

In the specific period display mode, the medical image diagnosticapparatus 1 according to this embodiment can display a temporal changeof the FFR result of a coronary artery that is limited to a specificperiod in one cycle of heart beats. In the thinning processing mode, themedical image diagnostic apparatus 1 according to this embodiment candisplay a temporal change of the FFR result of the coronary artery in astate in which variations of the FFR value per unit time are decreasedby adjusting the thinning ratio. In the local display mode, only an areaof user's interest (angiostenosis position, blood vessel branchposition, and range of a blood vessel having a predetermined width ormore) is displayed in a color corresponding to the magnitude of the FFRvalue. To the contrary, an area of no interest excluding the area ofinterest is not displayed in color, and a morphological image isdisplayed directly. Hence, the user can interpret a temporal change ofthe FFR result regarding the area of interest of the coronary artery. Inthe blood vessel display mode, the medical image diagnostic apparatus 1according to this embodiment can display a temporal change of the FFRresult of each blood vessel. In the FFR value-limited mode, only a rangecorresponding to a set FFR value range is displayed in a colorcorresponding to the magnitude of the FFR value. In a range excludingthe set FFR value range, a morphological image is directly displayed.Thus, the user can interpret a temporal change of the FFR resultregarding an area corresponding to an FFR value range of interest. Forthe purpose of conversion from an FFR distribution map into a color map,an LUT registered in advance may be used, or another LUT generated basedon an FFR value included in the color map of a display target asdescribed above may be used. The LUT and the other LUT have differentFFR value ranges included in a correspondence table. For example, theupper limit value of the FFR value is 1 and its lower limit value is 0.2in the LUT, whereas the upper limit value of the FFR value is 1 and itslower limit value is 0.7 or the like in the other LUT. The use of theother LUT makes it easy to see the distribution of FFR values on thecolor map of a display target.

Each of the plurality of display modes and display methods describedabove is a display mode corresponding to one of three types oflimitations: the limitation of the number of superposed images to bedisplayed; the limitation of a range to be displayed; and the limitationof a range to be displayed in color. These limitations aim to make iteasy to see a temporal change of the FFR result of a coronary arterythat changes quickly. The medical image diagnostic apparatus 1 havingthe above-described display modes according to this embodiment canimprove the image interpretation efficiency of a user on a displayregarding a temporal change of the FFR result.

(Modification)

A medical image diagnostic apparatus 1 according to a modification ofthis embodiment will be explained with a focus on a difference from themedical image diagnostic apparatus 1 according to this embodiment.

FIG. 10 is a block diagram showing an example of the arrangement of themedical image diagnostic apparatus 1 according to the modification ofthis embodiment. As shown in FIG. 10, the difference from the medicalimage diagnostic apparatus 1 according to this embodiment is that animage processing circuitry 21 is added to the building components.

The storage memory 12 stores a plurality of volume data constituting atime series regarding a cardiac muscle to which the coronary artery ofan object supplies blood. The volume data are collected by a CTapparatus, an MRI apparatus, a SPECT apparatus, a PET apparatus, and thelike.

The image processing circuitry 21 is processing circuitry that generatesa plurality of functional images respectively corresponding in phase toa plurality of superposed images based on the plurality of volume datastored in the storage memory 12. The image processing circuitry 21 readsa program corresponding to an image processing function from storagememory 12, and executes the program to realize the image processingfunction.

Functional images are, for example, a myocardial perfusion image and apolar map.

The display 20 performs position matching of a plurality of superposedimages obtained by superposing a plurality of color maps and a pluralityof morphological images respectively corresponding in phase to theplurality of color maps, and displays them over a plurality offunctional images respectively corresponding in phase to the superposedimages. Note that FIG. 5 shows a display example using a myocardialperfusion as a functional image, and FIG. 6 shows a display exampleusing a polar map as a functional image.

In the medical image diagnostic apparatus 1 according to thisembodiment, the storage memory 12 stores in advance data of functionalimages, for example, data of a myocardial perfusion image and data of apolar map. To the contrary, in the medical image diagnostic apparatus 1according to the modification of this embodiment, the storage memory 12stores a plurality of volume data constituting a time series regarding acardiac muscle to which the coronary artery of an object supplies blood.The image processing circuitry 21 can appropriately generate functionalimages, for example, a myocardial perfusion image and polar map inaccordance with a user instruction. When the display 20 displays asuperposed image over a functional image, the medical image diagnosticapparatus 1 according to this modification can improve the degree offreedom of display much more than in the medical image diagnosticapparatus 1 according to this embodiment.

The above described “processing circuitry” means, for example, a centralprocessing unit (CPU), a graphics processing unit (CPU), an applicationspecific integrated circuit (ASIC), a programmable logical device (e.g.,a simple programmable logic device (SPLD), a complex programmable logicdevice (CPLD), and a field programmable gate array (FPGA)), or the like.

Note that programs may be directly incorporated in processing circuitryinstead that programs are stored in storage memory 12. In this case, theprocessing circuitry reads programs incorporated in circuitry andexecutes the programs to realizes predetermined functions.

Each function (each component) in the present embodiment is notnecessary to be corresponded to a single processing circuit and may berealized by a plurality of processing circuits. To the contrary, forexample, at least two functions (at least two components) may berealized by a single processing circuit. Further, a plurality offunctions (a plurality of components) may be realized by a singleprocessing circuit.

While the embodiment of the inventions has been described, theembodiment has been presented by way of an example only, and is notintended to limit the scope of the inventions. Indeed, the embodimentmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes may be made without departing fromthe spirit of the inventions. The appended claims and their equivalentsare intended to cover such forms or modifications as would fall withinthe scope and spirit of the inventions. For example, the processingregarding switching of the color map, which is included in theflowcharts shown in FIGS. 2, 3, and 9, can be omitted. In the embodimentand the modification of the embodiment, a target (range) to be displayedin color on a color map is automatically limited based on an FFR value,an angiostenosis position, a blood vessel branch position, and the areaof a blood vessel having a predetermined width or more, and a superposedimage to be displayed is automatically limited from a plurality ofsuperposed images based on the heart beat phase. However, a target to beconverted into a color map may be limited by the same method. Theseembodiments and their modifications are incorporated in the scope andsprit of the present invention, and are also incorporated in the scopeof the invention and its equivalents defined in the appended claims.

1. A medical image processing apparatus comprising: processing circuitryconfigured to acquire a morphological image including at least a part ofa coronary artery and a blood vessel branch of the coronary artery,acquire a Fractional Flow Reserve (FFR) distribution regarding at leastthe part of the coronary artery, and generate a color coded map whichrepresents the FFR distribution by determining a boundary between acolor-display region and a non-color-display region based on a positionof the blood vessel branch of the coronary artery, displaying, in thecolor-display region, color representing the FFR distribution, and notdisplaying, in the non-color-display region, the color representing theFFR distribution.
 2. The medical image processing apparatus according toclaim 1, wherein the non-color-display region is set based on a rangefrom the blood vessel branch position.
 3. The medical image processingapparatus according to claim 1, wherein the processing circuitryacquires data of a plurality of FFR distributions regarding a coronaryartery.
 4. The medical image processing apparatus according to claim 3,wherein the processing circuitry sets, as the non-color-display region,ranges respectively specified from the plurality of FFR distributionsbased on an FFR value.
 5. The medical image processing apparatusaccording to claim 1, wherein the processing circuitry specifies atleast one of an angiostenosis position of the coronary artery, a bloodvessel branch position, and a position of a blood vessel having not lessthan a predetermined width from the morphological image, and theprocessing circuitry sets, as the non-color-display region, rangesspecified from the corresponding color coded map based on at least oneof the angiostenosis position, the blood vessel branch position, and theposition of the blood vessel having not less than the predeterminedwidth.
 6. The medical image processing apparatus according to claim 3,wherein the plurality of FFR distributions comprise at least two timephases included in one cycle of heart beats, and the processingcircuitry sets, as the non-color-display region, the corresponding colorcoded map based on a heartbeat phase.
 7. The medical image processingapparatus according to claim 3, wherein the processing circuitrygenerates data of a correspondence table that associates data of aplurality of colors respectively with a plurality of FFR values definedby upper limit values and lower limit values of FFR values included inthe plurality of FFR distributions, and the processing circuitrygenerates a plurality of color coded maps which represents the pluralityof FFR distributions based on the correspondence table, respectively. 8.The medical image processing apparatus according to claim 3, wherein theprocessing circuitry generates data of another correspondence table thatassociates data of a plurality of colors respectively with a pluralityof FFR values defined by upper limit values and lower limit values ofFFR values included in the non-color-display region for the plurality ofcolor coded maps, and the processing circuitry generates a plurality ofcolor coded maps which represents the plurality of FFR distributionsbased on the correspondence table, respectively.
 9. The medical imageprocessing apparatus according to claim 3, wherein the processingcircuitry generates data of a correspondence table that associates dataof a plurality of colors respectively with a plurality of FFR valuesdefined by upper limit values and lower limit values of FFR valuesincluded in the plurality of FFR distributions, and data of anothercorrespondence table that associates data of a plurality of colorsrespectively with a plurality of FFR values defined by upper limitvalues and lower limit values of FFR values included in thenon-color-display region for the plurality of color maps, and theprocessing circuitry switches, in accordance with a user instruction,color coded maps to be displayed over the plurality of morphologicalimages, out of a plurality of color coded maps generated based on thecorrespondence table and a plurality of color coded maps generated basedon the other correspondence table.
 10. The medical image processingapparatus according to claim 1, wherein the processing circuitry isconfigured to acquire volume data regarding a cardiac muscle to whichthe coronary artery supplies blood, generate, based on the volume data,a functional image regarding the cardiac muscle, and generate superposedimage obtained by position matching of the functional image and thecolor coded map.
 11. The medical image processing apparatus according toclaim 10, wherein the functional image includes a myocardial perfusionimage or a polar map.
 12. The medical image processing apparatusaccording to claim 1, wherein the processing circuitry is configured toacquire data of a functional image regarding a cardiac muscle to whichthe coronary artery supplies blood, and generate superposed imageobtained by position matching of the functional image and the colorcoded map.
 13. The medical image processing apparatus according to claim12, wherein the functional image includes a myocardial perfusion imageor a polar map.
 14. A computer implemented method comprising: acquiringa morphological image including at least a part of a coronary artery anda blood vessel branch of the coronary artery; acquiring a FractionalFlow Reserve (FFR) distribution regarding at least the part of thecoronary artery, and generating a color coded map which represents theFFR distribution by determining a boundary between a color-displayregion and a non-color-display region based on a position of the bloodvessel branch of the coronary artery, displaying, in the color-displayregion, color representing the FFR distribution, and not displaying, inthe non-color-display region, the color representing the FFRdistribution.
 15. A medical image processing apparatus comprising:processing circuitry configured to acquire a morphological imageincluding at least a part of a coronary artery, acquire a FractionalFlow Reserve (FFR) distribution regarding at least the part of thecoronary artery, and generate a color coded map which represents the FFRdistribution by determining a boundary between a color-display regionand a non-color-display region based on a vascular diameter of thecoronary artery, displaying, in the color-display region, colorrepresenting the FFR distribution, and not displaying, in thenon-color-display region, the color representing the FFR distribution.16. The medical image processing apparatus according to claim 15,wherein the non-color-display region is set based on an area of acoronary artery of which vascular diameter has a predetermined width orless.
 17. A computer implemented method comprising: acquiring amorphological image including at least a part of a coronary artery,acquiring a Fractional Flow Reserve (FFR) distribution regarding atleast the part of the coronary artery, and generating a color coded mapwhich represents the FFR distribution by determining a boundary betweena color-display region and a non-color-display region based on avascular diameter of the coronary artery, displaying, in thecolor-display region, color representing the FFR distribution, and notdisplaying, in the non-color-display region, the color representing theFFR distribution.
 18. A medical image processing apparatus comprising:processing circuitry configured to acquire a morphological imageincluding at least a part of a coronary artery and a blood vessel branchof the coronary artery, acquire a Fractional Flow Reserve (FFR)distribution regarding at least the part of the coronary artery,generate data of a correspondence table that associates data of aplurality of colors respectively with a plurality of FFR values definedby upper limit values and lower limit values of FFR values included inthe FFR distribution, and generate a color coded map which representsthe FFR distribution by determining a boundary between a color-displayregion and a non-color-display region based on a position of the bloodvessel branch of the coronary artery, displaying, in the color-displayregion, color representing the FFR distribution based on thecorrespondence table, and not displaying, in the non-color-displayregion, the color representing the FFR distribution.
 19. A medical imageprocessing apparatus comprising: processing circuitry configured toacquire a morphological image including at least a part of a coronaryartery and a blood vessel branch of the coronary artery, acquire aFractional Flow Reserve (FFR) distribution regarding at least the partof the coronary artery, generate data of a correspondence table thatassociates data of a plurality of colors respectively with a pluralityof FFR values defined by upper limit values and lower limit values ofFFR values included in the FFR distribution, and generate a color codedmap which represents the FFR distribution by determining a color-displayregion based on a position of the blood vessel branch of the coronaryartery, and displaying, in the color-display region, color representingthe FFR distribution based on the correspondence table.
 20. A medicalimage processing apparatus comprising: processing circuitry configuredto acquire a morphological image including at least a part of a coronaryartery and a blood vessel branch of the coronary artery, acquire aFractional Flow Reserve (FFR) distribution regarding at least the partof the coronary artery, acquire data of a functional image regarding acardiac muscle to which the coronary artery supplies blood, generate acolor coded map which represents the FFR distribution by determining acolor-display region based on a position of the blood vessel branch ofthe coronary artery, and displaying, in the color-display region, colorrepresenting the FFR distribution, and generate superposed imageobtained by position matching of the functional image and the colorcoded map.